Threshold and sill assemblies have long been used beneath entranceway doors to provide a variety of advantages including the prevention of heat loss under the door and the draining of rain water away from the entranceway. For many years, such assemblies have been constructed of wood and typically include an upwardly extending threshold cap portion positioned to engage a metal or rubber-like weather strip or wiper secured along the bottom of the closed door to create a seal against heat loss. While such wooden threshold assemblies are adequate for their intended purposes, they nevertheless tend to be susceptible over time to wear and tear and to expansion, contraction, and rot as a result of the continuously changing moisture conditions in the atmosphere. As a result, wooden threshold assemblies eventually become ineffective and require replacement.
In recent years, threshold assemblies constructed of extruded aluminum or aluminum alloys have been introduced as alternatives to their wooden counterparts. Many of these aluminum assemblies include a wood, plastic, or aluminum threshold cap that underlies a closed door and that can be adjusted up or down at the time the door unit is installed to insure a tight fit between the door bottom and the cap. Further, if the originally established fit between the cap and door bottom deteriorates over time because of wear of the cap or settlement of the dwelling, the threshold cap of these assemblies can simply be readjusted to bring the fit back to its original integrity. Examples of aluminum threshold and sill assemblies of the type discussed are found in U.S. Pat. Nos. 4,447,987 of Lesosky, 3,762,100 of Kimpel 3,273,287 of Pease, 3,967,412 of Governale, and 4,352,258 of Bursk et.al.
Extruded aluminum sill and threshold assemblies have generally represented improvements over wooden thresholds because of their resistance to wear and tear and because they do not rot or otherwise deteriorate over time. Nevertheless, such assemblies have typically been plagued by a number problems and shortcomings inherent in their own respective designs. Specifically, even though a gasket is usually provided along the interface between the threshold cap and the aluminum body of the sill, rain water still tends to seep through the interface and thus leak under the cap and into the region beneath the assembly. Even more serious leaks can and many times do develop at the ends of these threshold and sill assemblies where they are secured to the bottoms of the vertical door frame jambs. Such leaks can be intensified during blowing rain storms and can eventually lead to serious rotting of flooring and structural joists that underlie the threshold assembly.
Another shortcoming of prior art aluminum threshold assemblies is that their associated threshold caps typically are vertically adjustable by means of a set of adjustment screws whose slotted heads protrude through corresponding holes in the top of the threshold cap While this arrangement provides for easy adjustment with a simple screwdriver, the holes through which the screw heads protrude provide yet another pathway for water to seep through and under the threshold cap to deteriorate flooring thereunder Furthermore, the holes and adjustment screw heads tend to fill with dirt and debris over time, which can be unsightly, unsanitary, and can make it difficult to perform the adjustments for which the screws are intended.
Thus, a continuing and heretofore unaddressed need exists for an improved threshold and door sill assembly that effectively prevents seepage of rainwater through and around the assembly and that has an adjustable threshold cap that is void of holes through which water can leak and that has no exposed adjustment means to collect dirt. The present invention is such an assembly.